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<a href="async__fwd_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;<a class="code" href="detail_2async__fwd_8hpp.html">flow/async/detail/async_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &quot;<a class="code" href="util__fwd_8hpp.html">flow/util/util_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="preprocessor">#include &quot;<a class="code" href="sched__task__fwd_8hpp.html">flow/util/sched_task_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="preprocessor">#include &lt;boost/any.hpp&gt;</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span> </div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment"></span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="comment">/**</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="comment"> * Flow module containing tools enabling multi-threaded event loops operating under the asynchronous-task proactor</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment"> * pattern, by providing a streamlined API around boost.asio event loops with added advanced task- and</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment"> * thread-scheduling features.  There is also support for single-threaded event loops.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment"> *</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * In simpler terms, at its core -- including when the &quot;pool&quot; has just one thread, which</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> * is very common -- it provides a compact way of both starting thread(s) *and* posting/scheduling tasks and I/O</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> * to run in such thread(s).  By default one must worry about each of those 2 concerns separately and decide how</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * exactly to hook them up; which is not rocket science, but it *is* a ton of boiler-plate, and it *is* easy to</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * make mistakes and/or omit useful startup/shutdown practices, logging, and more.  This module provides, via</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * Concurrent_task_loop and its implementations, at least that consistency/standardization.  Plus, it provides</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> * certain advanced features as mentioned above.</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> *</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> *   - boost.asio provides the core algorithmic abilities of an optionally multi-threaded task-executing loop,</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> *     particularly through classes util::Task_engine (a/k/a `boost::asio::io_context`), util::Strand</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> *     (a/k/a `strand` in `boost::asio`), and util::Timer.  flow::async Flow module somewhat streamlines</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> *     this API in such a way as to keep the user&#39;s focus on their conceptual async-task-driven algorithm as opposed</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> *     to details of threads, handlers, cores, etc.  The async::Op opaque type is central to this streamlined API,</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> *     plus the central class Concurrent_task_loop.</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> *     - The bottom line is the user thinks about their algorithm in</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> *       terms of tasks; while the internals of the chosen Concurrent_task_loop concrete object worry about the</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> *       actual scheduling of these tasks across threads.</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> *   - boost.asio doesn&#39;t really provide ways to specify how threads should be assigned to processor cores; it only</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> *     controls what code is executed on which thread.  These abilities are available natively.  flow::async Flow</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> *     module allows one to set certain knobs controlling this behavior, and the user can continue to only worry</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> *     about their algorithm and not threading details.</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> *     - The combination of the generalized async::Op mechanism and these thread-hardware-scheduling features</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> *       in an integrated whole is what hopefully makes the Flow `async` module a value-add over just boost.asio,</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> *       or over just boost.asio with some thread-core-affinity utility functions on the side.</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> *</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> * @see The central type is the interface class Concurrent_task_loop.  For single-thread async work,</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> *      which is very common, see Single_thread_task_loop, a simplified adapter, similar to how `std::queue&lt;T&gt;`</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> *      is commongly a simplified `std::deque&lt;T&gt;` or `list` underneath.</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> * @see async::Op.</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> *</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> *</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> * @todo The thread-to-core optimizations provided at this time are, at least, a good start, but more advanced logic</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> * can be devised with more low-level experience and/or by using certain open-source libraries.  It&#39;s possible that</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> * a more knowledgeable person would devise more or better knobs and/or require less manual specification of</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> * values.  The following background reading may help devise</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> * more advanced logic and/or knobs:</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> * [ https://eli.thegreenplace.net/2016/c11-threads-affinity-and-hyperthreading/ |</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> * https://mirrors.edge.kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.2016.07.31a.pdf |</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * https://lwn.net/Articles/255364/ | &quot;hwloc&quot; library (portable lib for detailed hardware topology info) |</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * libNUMA ].</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> */</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno"><a class="line" href="namespaceflow.html">   74</a></span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1async.html">flow::async</a></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>{</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span> </div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment">// Find doc headers near the bodies of these compound types.</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span> </div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="keyword">class </span>Cross_thread_task_loop;</div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="keyword">class </span>Concurrent_task_loop;</div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="keyword">class </span>Op_list;</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="keyword">class </span>Segregated_thread_task_loop;</div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="keyword">class </span>Single_thread_task_loop;</div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="keyword">class </span>Timed_single_thread_task_loop;</div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="keyword">class </span>Timed_concurrent_task_loop;</div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Time_accumulator&gt;</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="keyword">class </span>Timed_concurrent_task_loop_impl;</div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"></span> </div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment">/**</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> * Short-hand for a task that can be posted for execution by a Concurrent_task_loop or flow::util::Task_engine;</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> * it is simply something callable via `()` with no arguments and returning nothing.</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> *</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> * By convention in comments we represent `Task`s with the letters F, G, H.</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> */</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#af35fb65bdea1a3a92929ec2c4a6a6b72">   96</a></span><span class="keyword">using </span><a class="code hl_class" href="classflow_1_1Function.html">Task</a> = <a class="code hl_class" href="classflow_1_1Function.html">Function</a>&lt;void ()&gt;;</div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"></span> </div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment">/**</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> * An object of this opaque type represents a collection of 1 or more async::Task, past or future, such that:</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> * *if* one performs `C-&gt;post(J, F)` and `C-&gt;post(K, G)` (where C is `Concurrent_task_loop*`, JK are the same</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> * `async::Op&amp;`, or one refers to a transitive copy of the other, and FG are both `Task`s), *then*</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment"> * F and G will NOT execute concurrently.</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment"> *</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"> * In addition, it is guaranteed that copying (via constructor or assignment) of async::Op is</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment"> * has performance characteristics no worse than those of `shared_ptr`.  I.e., it is to be thought of as light-weight.</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment"> *</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment"> * The value `Op()` is designated as a null/sentinel value and must not be passed to Concurrent_task_loop::post()</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment"> * or anything built on it.</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment"> *</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment"> * That&#39;s the formal definition.  We reiterate that copying these is cheap; and moreover two `Op`s such that</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment"> * one is a copy (of a copy, of a copy, of a copy...) of another, then these are conceptually isomorphic: they</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment"> * represent the same op, or collection of `Task`s that must never execute concurrently.  Finally, tip: Don&#39;t think</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment"> * of an `Op` as a collection of 2+ `Task`s; but rather a tag or label that associates 2+ `Task`s with each other.</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment"> * (Also, nothing prevents an async::Task being a part of 2+ `Op`s simultaneously, though informally speaking</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment"> * it&#39;s arguably best not to make code maintainers grok such a design.)</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment"> *</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment"> * By convention in comments we represent `Op`s with the letters J, K, L.</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment"> *</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment"> * ### When to use an `Op` versus just a stand-alone `Task`? ###</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment"> * When choosing a Concurrent_task_loop::post() (the one with `Op` vs. one without; or similar choices in more</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment"> * advanced cases), here are some things to remember.  These can be derived independently and are only included</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment"> * as a convenience/refresher:</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment"> *</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment"> *   - An `Op` prevents `Task`s from executing concurrently.  If there is exactly 1 thread in a pool, then they couldn&#39;t</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment"> *     anyway, so an `Op` is not needed...</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment"> *     - ...except as future-proofing, in case conceivably 1 thread might soon turn into 2+ after all.</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment"> *   - It is quite common to follow the pattern wherein, as the very last statement to execute within a `Task`,</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment"> *     one `post()`s (or similar) exactly 1 `Task` to asynchronously execute next.  Since it&#39;s the last statement,</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment"> *     and `post()` and similar are explicitly thread-safe, this ensures the current and next `Task`s do not execute</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment"> *     concurrently.  So an `Op` is not needed...</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment"> *     - ...except as future-proofing.  It is sometimes easier to maintain, and more expressive to read, when many</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment"> *       `Task`s are &quot;officially&quot; run under the banner of a single `Op`, even if some parts of the async handling of</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment"> *       the &quot;conceptual&quot; operation are serial and hence don&#39;t technically require an `Op`.  Example: In a web</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment"> *       server it is reasonable to create an `Op` for the entire request, with all `Task`s (even serially called ones)</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment"> *       being associated with that per-request `Op`; then, simply, no locking is necessary for per-request data</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment"> *       structure(s).  It&#39;s much easier to explain, &quot;you don&#39;t need to lock &#39;em,&quot; vs. &quot;you don&#39;t need to lock &#39;em,</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment"> *       unless the logic changes in such a way as to....&quot;</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment"> *</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment"> * To be fair, those tips ignore performance; they implicitly assume using `Op` pointlessly (functionally, not</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"> * stylistically, so) is otherwise &quot;free.&quot;  It is *not* free; depending on internal details using `Op` might involve</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment"> * a util::Strand and/or pinning stuff to a specific thread.  Informally, this is seldom a big deal in practice;</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment"> * but in performance-sensitive projects one must remember there is a cost.</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment"> *</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment"> *</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment"> * `boost::any` (storing nothing heavier-weight than a `shared_ptr` to satisfy that explicit guarantee above) is one</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment"> * way to do this.  A rigid polymorphic hierarchy (`virtual`) is another.  Performance-wise they&#39;re similar, costing</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"> * essentially a single `virtual` pointer lookup per Concurrent_task_loop::post().  boost.any is much pithier, not</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment"> * requiring a class hierarchy at all, and otherwise it&#39;s pretty much the same in terms of how they&#39;re used internally.</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"> * Some might say the polymorphic hierarchy is clearer, because it is explicit, but I feel comments alone, too, can</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"> * be just as clear, and brevity is a virtue.</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment"> */</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">  153</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">Op</a> = boost::any;</div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment"></span> </div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment">/**</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"> * Similar to flow::async::Task but used for scheduled-in-future tasks as opposed to to-be-run-ASAP tasks.</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment"> * In practice it&#39;s the same thing but takes a single `bool` argument with the meaning explained</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment"> * in util::schedule_task_from_now() doc header (spoiler alert: whether it ran as scheduled or was short-fired by</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment"> * user, as of this writing).</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment"> *</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment"> * @note Whenever a comment explains how `Task`s are dealt with, one may usually assume the same extends equally to</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment"> *       a `Scheduled_task`, merely at a different point in time.  We omit that explicit language for brevity;</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment"> *       it is to be assumed.</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment"> */</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#af8c06052dd887bc77444550a7c243154">  165</a></span><span class="keyword">using </span><a class="code hl_class" href="classflow_1_1Function.html">Scheduled_task</a> = <a class="code hl_typedef" href="namespaceflow_1_1util.html#aafa03984c5012ef7db2e7d01b6909a83">util::Scheduled_task</a>;</div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"></span> </div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment">/**</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment"> * Short-hand for a boost.asio completion handler: The minimal type, taking only a flow::Error_code</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"> * a/k/a `boost::system::error_code`.</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment"> */</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#afdf5986cd6dc055673792890502135a8">  171</a></span><span class="keyword">using </span><a class="code hl_class" href="classflow_1_1Function.html">Task_asio_err</a> = <a class="code hl_class" href="classflow_1_1Function.html">Function</a>&lt;void (<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>&amp;)&gt;;</div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment"></span> </div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment">/**</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment"> * Short-hand for a boost.asio completion handler: The type that takes a `size_t` count of things successfully</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> * transferred usually.</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> */</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#a3808f400a39b77d712e0526fa412bf57">  177</a></span><span class="keyword">using </span><a class="code hl_class" href="classflow_1_1Function.html">Task_asio_err_sz</a> = <a class="code hl_class" href="classflow_1_1Function.html">Function</a>&lt;void (<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>&amp;, <span class="keywordtype">size_t</span>)&gt;;</div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"></span> </div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment">/**</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment"> * Short-hand for reference-counting pointer to a mutable util::Task_engine (a/k/a `boost::asio::io_context`).</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment"> * This is generally how classes in the Concurrent_task_loop hierarchy refer to their internally used</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment"> * `Task_engine`s but also in advanced cases may be communicated to their user.</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"> *</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment"> *</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span><span class="comment"> * ### Rationale ###</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment"> * Why do that instead of using raw `Task_engine*`?  It may not be obvious as you read</span></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment"> * this now, but all kinds of pain goes away due to the possibilities of who</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="comment"> * happens to own an underlying `Task_engine` -- it can be shared by all threads in pool, or each can have its own</span></div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment"> * `Task_engine`, depending on the chosen Concurrent_task_loop subclass -- and in what order those things</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment"> * might execute their destructors.  By simply using a `shared_ptr&lt;&gt;` everywhere, with small overhead we ensure</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span><span class="comment"> * an underlying `Task_engine` does not get destroyed until everything that uses it is destroyed first, and</span></div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment"> * that could be a number of things.  By using `shared_ptr&lt;&gt;` we needn&#39;t break our heads worrying about executing</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment"> * de-init pieces of code in just the right order just to avoid early-free.  (This is said from experience.)</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment"> *</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment"> * This is reinforced in those semi-advanced cases where a `Task_engine` is passed to user via public API.</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment"> */</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#a968806f54b14c697fd76b3339a2bdbbf">  198</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceflow_1_1async.html#a968806f54b14c697fd76b3339a2bdbbf">Task_engine_ptr</a> = boost::shared_ptr&lt;util::Task_engine&gt;;</div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment"></span> </div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment">/**</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment"> * Short-hand for ref-counted pointer to util::Strand.</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment"> *</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment"> *</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment"> * ### Rationale ###</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span><span class="comment"> * We at times return new `Strand`s (Cross_thread_task_loop::create_op()), so universally use ref-counted pointers</span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment"> * to `Strand`s to not have to worry about `Strand` lifetimes too hard.</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment"> *</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment"> * Key fact: The type Cross_thread_task_loop loads into superclass&#39;s async::Op (`boost::any`) is `Strand_ptr`.</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span><span class="comment"> * That is, a `Strand` is the mechanism used to bundle together non-concurrent tasks in Cross_thread_task_loop.</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment"> */</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#a2b92feccafa90bce16db57131c0fcd9e">  212</a></span><span class="keyword">using </span><a class="code hl_typedef" href="namespaceflow_1_1async.html#a2b92feccafa90bce16db57131c0fcd9e">Strand_ptr</a> = boost::shared_ptr&lt;util::Strand&gt;;</div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span><span class="comment"></span> </div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span><span class="comment">/**</span></div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment"> * Enumeration indicating the manner in which asio_exec_ctx_post(), and various boost.asio &quot;post&quot; operations like</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment"> * it or based on it, are to actually execute the given task in relation to when the &quot;posting&quot; routine, itself,</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment"> * returns control to its caller.  Basically it indicates whether the execution should be synchronous or asynchronous</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment"> * and how, if it all, to wait for its completion -- or its initiation.</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment"> * The `enum` members&#39; meanings are the key things to understand;</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment"> * and there&#39;s some discussion in their doc headers that might be useful as a boost.asio refresher.</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment"> */</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno"><a class="line" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">  222</a></span><span class="keyword">enum class</span> <a class="code hl_enumeration" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">Synchronicity</a></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span>{<span class="comment"></span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment">   * Simply post the given task to execute asynchronously in some execution context -- as soon as the context&#39;s</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment">   * scheduler deems wise but specifically *not* inside the posting routine itself; and return as soon as possible</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">   * having thus posted it.  That is: work in the manner of boost.asio `post(Task_engine, F)`.</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment">   *</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment">   * In particular, suppose you&#39;re calling `POST(F)` in this mode, where</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment">   * `POST()` is some posting routine controlling a thread pool P, and `F()` is the task; and suppose the scheduler</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment">   * would deem wise to run `F()` in some thread P.W in that pool (perhaps for load-balancing reasons).  Then:</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">   *   - If `POST()` is being called outside of pool P, or it is being called from a sibling</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment">   *     thread P.W&#39; but not W itself, then `F()` will run at some point in the future (possibly even</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment">   *     concurrently with `POST()` itself), in thread P.W.</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment">   *     - One typical case is when some external user of P loads work onto P.</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span><span class="comment">   *     - The other is if some task or completion handler already in P loads async work back</span></div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span><span class="comment">   *       onto its own pool P, but the scheduler decides it&#39;s best for it to run in a different thread than</span></div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span><span class="comment">   *       the posting code.</span></div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span><span class="comment">   *       - This is only possible with 2 or more threads in P (by no means always the case).</span></div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment">   *   - If `POST()` is being called from W itself, meaning the scheduler decided that the task should load</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment">   *     on the same thread as the posting task, then `F()` will run at some point in the future strictly after the</span></div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="comment">   *     `POST()` returns.</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment">   *     - This usually means some task or completion handler in pool P is loading async work back onto its own</span></div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">   *       pool, and either that pool contains only 1 thread (so there is no other choice), or else</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   *       the scheduler decided the calling thread is still the best choice for task `F()` at this time</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   *       (e.g., maybe the other thread(s) are loaded with queued work).</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment">   *</span></div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span><span class="comment">   * Either way, `POST()` will return quickly.  Then `F()` will either run concurrently or after this return -- but</span></div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span><span class="comment">   * never *in* `POST()` synchronously.</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment">   */</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span>  <a class="code hl_enumvalue" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485a4d7a5700444c0570af37b1f9bcc6eb1f">S_ASYNC</a>,</div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span><span class="comment"></span> </div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment">   * Same as Synchronicity::S_ASYNC but the posting routine then waits as long as necessary for the given task to</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">   * complete; and only then returns.  That is: work in the manner of boost.asio `post(Task_engine, F)`, but</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">   * wait until `F()` actually runs and returns.  This must only be used when posting from a thread *outside* the</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">   * target thread pool; or undefined behavior will result.</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment">   *</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">   * @warning One must *not* use this mode when posting onto a thread pool from inside</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">   *          that thread pool: boost.asio `post()`-like function by definition won&#39;t execute a task synchronously</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment">   *          inside itself, yet by the definition of this mode it must also wait for the task to run and complete.</span></div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment">   *          So if `post()` (or similar) were to decide the task belongs on the calling thread, an inifinite</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">   *          block (deadlock) occurs, as it will be waiting for something to happen that the wait prevents from</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   *          happening.</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment">   *</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">   * This mode is reminiscent of the promise/future concept and allows one to easily solve the age-old problem of</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   * &quot;how do I ask a thread/pool to do a thing and then wait for get a result?&quot;.  One might do this by manually</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   * using a promise/future pair; or even mutex/condition variable pair; but by using this such boiler-plate is</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   * reduced (along with fewer bugs).</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   *</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   * @warning Be aware that the wait for completion will block infinitely, if one were to do something that would</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   *          prevent the task from ever running.  When working with boost.asio `Task_engine`s, this may occur</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   *          when one `stop()`s or simply destroys the `Task_engine` (though the time period during which</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   *          one would have to do this is short, assuming the task is quick).  Naturally the way to avoid this is</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   *          by not stopping or destroying the execution context during a posting call in</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment">   *          mode `S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION`.  For example, the `Task_engine::stop()` call might</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment">   *          be placed in the same thread as the posting; then they cannot be concurrent.  If this is triggered from</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment">   *          a SIGTERM/INT handler, one might only set or post something that will trigger the destruction in an</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment">   *          orderly fashion at the proper time as opposed to doing it directly from the sig handler itself.</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment">   *          This warning isn&#39;t anything that should be particularly new -- orderly shutdown is typically concerned</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment">   *          with such logic anyway -- but it seemed worth putting in perspective of the fact this mode involves</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment">   *          a wait for something that doesn&#39;t necessarily ever run, unless you actively make sure it does.</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment">   *</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment">   * @todo Much like the promise/future mechanism provides optional timed wait functionality, it might make sense</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment">   * to provide the API ability to set an optional time limit for any wait invoked by</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment">   * Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION or Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_START.</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment">   * Probably best to add this only once a need clearly arises though.</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span><span class="comment">   */</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span>  <a class="code hl_enumvalue" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485a57525f29ac96f4edd56c951e7d7c7b25">S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION</a>,</div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment"></span> </div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span><span class="comment">   * Same as Synchronicity::S_ASYNC but the posting routine then waits as long as necessary for the given task to</span></div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span><span class="comment">   * *just* about to begin executing concurrently (so that any subsequent `Task_engine::stop()` shall be unable to</span></div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span><span class="comment">   * prevent it from executing and eventually finishing) -- and only then returns.</span></div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span><span class="comment">   *</span></div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span><span class="comment">   * This is most similar to `S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION` but may improve responsiveness of the</span></div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span><span class="comment">   * calling thread, if what one needs to achieve is a guarantee that `F()` *will definitely* execute and complete,</span></div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno">  298</span><span class="comment">   * but does *not* need to wait for this to happen.  So it&#39;s a weapon against a &quot;dangling&quot; `post()` that might</span></div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span><span class="comment">   * be followed immediately by `Task_engine::stop()` -- while not blocking until the posted thing finishes.</span></div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span><span class="comment">   *</span></div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span><span class="comment">   * @warning One must *not* use this mode when posting onto a thread pool from inside</span></div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span><span class="comment">   *          that thread pool; as with `S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION` that may hang the thread.</span></div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span><span class="comment">   */</span></div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span>  <a class="code hl_enumvalue" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485ae9a9ae292ea3fbbe3b313348dcec0846">S_ASYNC_AND_AWAIT_CONCURRENT_START</a>,</div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno">  305</span><span class="comment"></span> </div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00307" name="l00307"></a><span class="lineno">  307</span><span class="comment">   * Execute the given task synchronously, if the scheduler determines that the calling thread is in its thread pool</span></div>
<div class="line"><a id="l00308" name="l00308"></a><span class="lineno">  308</span><span class="comment">   * *and* is the best thread for the task; otherwise act identically to Synchronicity::S_ASYNC.  That is: work in the</span></div>
<div class="line"><a id="l00309" name="l00309"></a><span class="lineno">  309</span><span class="comment">   * manner of boost.asio `dispatch(Task_engine, F)`.  This can be useful for performance, since when the opportunity</span></div>
<div class="line"><a id="l00310" name="l00310"></a><span class="lineno">  310</span><span class="comment">   * presents itself this way avoids exiting a task only to immediately enter the posted task, when one could just</span></div>
<div class="line"><a id="l00311" name="l00311"></a><span class="lineno">  311</span><span class="comment">   * synchronously execute one after the other.</span></div>
<div class="line"><a id="l00312" name="l00312"></a><span class="lineno">  312</span><span class="comment">   *</span></div>
<div class="line"><a id="l00313" name="l00313"></a><span class="lineno">  313</span><span class="comment">   * @warning Do *not* presume to know when a given scheduler will actually decide it will invoke the given task</span></div>
<div class="line"><a id="l00314" name="l00314"></a><span class="lineno">  314</span><span class="comment">   *          synchronously, unless documentation very clearly explains such rules.  Just because it can does not</span></div>
<div class="line"><a id="l00315" name="l00315"></a><span class="lineno">  315</span><span class="comment">   *          mean it will.  For example, boost.asio `post()` says that the task &quot;might&quot; run synchronously when this is</span></div>
<div class="line"><a id="l00316" name="l00316"></a><span class="lineno">  316</span><span class="comment">   *          possible; not that it &quot;will.&quot;  Assumptions about when it might in fact do so can lead to subtle and</span></div>
<div class="line"><a id="l00317" name="l00317"></a><span class="lineno">  317</span><span class="comment">   *          difficult-to-reproduce bugs.  (Example of broken assumptions: Suppose it&#39;s a 1-thread pool, and one</span></div>
<div class="line"><a id="l00318" name="l00318"></a><span class="lineno">  318</span><span class="comment">   *          posts F from task G.  Surely it must run F synchronously -- there&#39;s no other thread!  But what if some</span></div>
<div class="line"><a id="l00319" name="l00319"></a><span class="lineno">  319</span><span class="comment">   *          other task or completion handler was already queued up to run before F was?  That&#39;s not even the point</span></div>
<div class="line"><a id="l00320" name="l00320"></a><span class="lineno">  320</span><span class="comment">   *          though; the scheduler is still free to not do it, say because of some spurious lock-related logic that</span></div>
<div class="line"><a id="l00321" name="l00321"></a><span class="lineno">  321</span><span class="comment">   *          is there for some obscure performance reason.)</span></div>
<div class="line"><a id="l00322" name="l00322"></a><span class="lineno">  322</span><span class="comment">   *</span></div>
<div class="line"><a id="l00323" name="l00323"></a><span class="lineno">  323</span><span class="comment">   * @warning If you choose to use this mode (or `dispatch()`-like routines in general), it is almost never a good idea</span></div>
<div class="line"><a id="l00324" name="l00324"></a><span class="lineno">  324</span><span class="comment">   *          to do so from anywhere except just before returning from a task (or from outside the thread pool).</span></div>
<div class="line"><a id="l00325" name="l00325"></a><span class="lineno">  325</span><span class="comment">   *          If called from the middle of a task, you now cannot be sure if A happens before B or B happens before A.</span></div>
<div class="line"><a id="l00326" name="l00326"></a><span class="lineno">  326</span><span class="comment">   *          Usually that makes things complicated unnecessarily.</span></div>
<div class="line"><a id="l00327" name="l00327"></a><span class="lineno">  327</span><span class="comment">   */</span></div>
<div class="line"><a id="l00328" name="l00328"></a><span class="lineno">  328</span>  <a class="code hl_enumvalue" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485aff6bc53ee6c14f2eee463c06d9dff01f">S_OPPORTUNISTIC_SYNC_ELSE_ASYNC</a></div>
<div class="line"><a id="l00329" name="l00329"></a><span class="lineno">  329</span>}; <span class="comment">// enum class Synchronicity</span></div>
<div class="line"><a id="l00330" name="l00330"></a><span class="lineno">  330</span> </div>
<div class="line"><a id="l00331" name="l00331"></a><span class="lineno">  331</span><span class="comment">// Free functions.</span></div>
<div class="line"><a id="l00332" name="l00332"></a><span class="lineno">  332</span><span class="comment"></span> </div>
<div class="line"><a id="l00333" name="l00333"></a><span class="lineno">  333</span><span class="comment">/**</span></div>
<div class="line"><a id="l00334" name="l00334"></a><span class="lineno">  334</span><span class="comment"> * An extension of boost.asio&#39;s `post()` and `dispatch()` free function templates, this free function template</span></div>
<div class="line"><a id="l00335" name="l00335"></a><span class="lineno">  335</span><span class="comment"> * allows the user to more easily select the synchronicity behavior as the given task is posted onto the</span></div>
<div class="line"><a id="l00336" name="l00336"></a><span class="lineno">  336</span><span class="comment"> * given execution context (util::Task_engine or util::Strand at least).  It also adds TRACE logging including</span></div>
<div class="line"><a id="l00337" name="l00337"></a><span class="lineno">  337</span><span class="comment"> * that book-ending the task&#39;s execution (aiding debugging, etc.).  The `synchronicity` argument controls the</span></div>
<div class="line"><a id="l00338" name="l00338"></a><span class="lineno">  338</span><span class="comment"> * specific way in which `task` is posted onto `*exec_ctx`; see #Synchronicity doc header.</span></div>
<div class="line"><a id="l00339" name="l00339"></a><span class="lineno">  339</span><span class="comment"> *</span></div>
<div class="line"><a id="l00340" name="l00340"></a><span class="lineno">  340</span><span class="comment"> * This call causes `task` to execute in a thread controlled by `*exec_ctx`.  The latter, at this time, must be</span></div>
<div class="line"><a id="l00341" name="l00341"></a><span class="lineno">  341</span><span class="comment"> * either util::Task_engine or util::Strand (which itself is born of a `Task_engine`).  It is likely that it will</span></div>
<div class="line"><a id="l00342" name="l00342"></a><span class="lineno">  342</span><span class="comment"> * work equally well for other entities satisfying the boost.asio `ExecutionContext` concept (see boost.asio docs), but</span></div>
<div class="line"><a id="l00343" name="l00343"></a><span class="lineno">  343</span><span class="comment"> * this is untested and not thought through formally, so officially such uses cause undefined behavior as of this</span></div>
<div class="line"><a id="l00344" name="l00344"></a><span class="lineno">  344</span><span class="comment"> * writing.</span></div>
<div class="line"><a id="l00345" name="l00345"></a><span class="lineno">  345</span><span class="comment"> *</span></div>
<div class="line"><a id="l00346" name="l00346"></a><span class="lineno">  346</span><span class="comment"> * Semantics can be found in #Synchronicity doc headers which are required reading before using this function.</span></div>
<div class="line"><a id="l00347" name="l00347"></a><span class="lineno">  347</span><span class="comment"> * However, briefly and informally, the utility of this function is as follows:</span></div>
<div class="line"><a id="l00348" name="l00348"></a><span class="lineno">  348</span><span class="comment"> *   - `post()` works on a `Task_engine` or `Strand` already and equals</span></div>
<div class="line"><a id="l00349" name="l00349"></a><span class="lineno">  349</span><span class="comment"> *     mode Synchronicity::S_ASYNC; with this function you&#39;ll get some added debug logging as well.</span></div>
<div class="line"><a id="l00350" name="l00350"></a><span class="lineno">  350</span><span class="comment"> *   - `dispatch()` and Synchronicity::S_OPPORTUNISTIC_SYNC_ELSE_ASYNC are similarly related: same thing</span></div>
<div class="line"><a id="l00351" name="l00351"></a><span class="lineno">  351</span><span class="comment"> *     but more logging.</span></div>
<div class="line"><a id="l00352" name="l00352"></a><span class="lineno">  352</span><span class="comment"> *   - Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION equals a `post()` with a promise/future pair,</span></div>
<div class="line"><a id="l00353" name="l00353"></a><span class="lineno">  353</span><span class="comment"> *     wherein the caller performs `unique_future.wait()` after the `post()`, while the task always sets</span></div>
<div class="line"><a id="l00354" name="l00354"></a><span class="lineno">  354</span><span class="comment"> *     `promise.set_value()` just before returning (and, again, more logging).</span></div>
<div class="line"><a id="l00355" name="l00355"></a><span class="lineno">  355</span><span class="comment"> *   - Lastly, Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_START is similar, but the `promise.set_value()`</span></div>
<div class="line"><a id="l00356" name="l00356"></a><span class="lineno">  356</span><span class="comment"> *     executes just *before* executing `task()`.  Hence any tasks queued before `task()` will first execute</span></div>
<div class="line"><a id="l00357" name="l00357"></a><span class="lineno">  357</span><span class="comment"> *     (same as previous bullet); and *then* asio_exec_ctx_post() will return, just as `task()` begins executing</span></div>
<div class="line"><a id="l00358" name="l00358"></a><span class="lineno">  358</span><span class="comment"> *     as opposed to wait for its completion.</span></div>
<div class="line"><a id="l00359" name="l00359"></a><span class="lineno">  359</span><span class="comment"> *     This is useful to prevent `E.stop()` after our return (where `E` is the `Task_engine` that either is</span></div>
<div class="line"><a id="l00360" name="l00360"></a><span class="lineno">  360</span><span class="comment"> *     or produced `*exec_ctx`) will be too late to prevent `task()` from executing and completing.</span></div>
<div class="line"><a id="l00361" name="l00361"></a><span class="lineno">  361</span><span class="comment"> *</span></div>
<div class="line"><a id="l00362" name="l00362"></a><span class="lineno">  362</span><span class="comment"> * In all cases, one gets more logging and arguably a bit of syntactic sugar, but</span></div>
<div class="line"><a id="l00363" name="l00363"></a><span class="lineno">  363</span><span class="comment"> * `S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION` and `S_ASYNC_AND_AWAIT_CONCURRENT_START` in particular eliminate</span></div>
<div class="line"><a id="l00364" name="l00364"></a><span class="lineno">  364</span><span class="comment"> * quite a bit of tedious and hairy code and explanations.</span></div>
<div class="line"><a id="l00365" name="l00365"></a><span class="lineno">  365</span><span class="comment"> *</span></div>
<div class="line"><a id="l00366" name="l00366"></a><span class="lineno">  366</span><span class="comment"> * Lastly, if `*exec_ctx` is currently not running, then the semantics described in #Synchronicity doc header</span></div>
<div class="line"><a id="l00367" name="l00367"></a><span class="lineno">  367</span><span class="comment"> * still apply but are deferred until it does run.  In particular in mode</span></div>
<div class="line"><a id="l00368" name="l00368"></a><span class="lineno">  368</span><span class="comment"> * Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION and Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_START</span></div>
<div class="line"><a id="l00369" name="l00369"></a><span class="lineno">  369</span><span class="comment"> * this function shall not return until `*exec_ctx` at least</span></div>
<div class="line"><a id="l00370" name="l00370"></a><span class="lineno">  370</span><span class="comment"> * does begin running in at least 1 thread; while the other two modes reduce to `post()`, which returns immediately,</span></div>
<div class="line"><a id="l00371" name="l00371"></a><span class="lineno">  371</span><span class="comment"> * leaving `task()` to run once `*exec_ctx` starts.</span></div>
<div class="line"><a id="l00372" name="l00372"></a><span class="lineno">  372</span><span class="comment"> *</span></div>
<div class="line"><a id="l00373" name="l00373"></a><span class="lineno">  373</span><span class="comment"> * @tparam Execution_context</span></div>
<div class="line"><a id="l00374" name="l00374"></a><span class="lineno">  374</span><span class="comment"> *         util::Task_engine or util::Strand.  See note above regarding other possibilities.</span></div>
<div class="line"><a id="l00375" name="l00375"></a><span class="lineno">  375</span><span class="comment"> * @param logger_ptr</span></div>
<div class="line"><a id="l00376" name="l00376"></a><span class="lineno">  376</span><span class="comment"> *        Logger to use in this function.</span></div>
<div class="line"><a id="l00377" name="l00377"></a><span class="lineno">  377</span><span class="comment"> * @param exec_ctx</span></div>
<div class="line"><a id="l00378" name="l00378"></a><span class="lineno">  378</span><span class="comment"> *        The execution context controlling the thread pool onto which to load the `task` for ASAP execution.</span></div>
<div class="line"><a id="l00379" name="l00379"></a><span class="lineno">  379</span><span class="comment"> * @param synchronicity</span></div>
<div class="line"><a id="l00380" name="l00380"></a><span class="lineno">  380</span><span class="comment"> *        Controls the precise behavior.  See above.</span></div>
<div class="line"><a id="l00381" name="l00381"></a><span class="lineno">  381</span><span class="comment"> * @param task</span></div>
<div class="line"><a id="l00382" name="l00382"></a><span class="lineno">  382</span><span class="comment"> *        The task -- taking no arguments and returning no value -- to load onto `*exec_ctx`.</span></div>
<div class="line"><a id="l00383" name="l00383"></a><span class="lineno">  383</span><span class="comment"> */</span></div>
<div class="line"><a id="l00384" name="l00384"></a><span class="lineno">  384</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Execution_context&gt;</div>
<div class="line"><a id="l00385" name="l00385"></a><span class="lineno">  385</span><span class="keywordtype">void</span> <a class="code hl_function" href="namespaceflow_1_1async.html#a24567271e97a67d3cae6bd8bf8dc63c4">asio_exec_ctx_post</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, Execution_context* exec_ctx, <a class="code hl_enumeration" href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">Synchronicity</a> synchronicity, <a class="code hl_typedef" href="namespaceflow_1_1async.html#af35fb65bdea1a3a92929ec2c4a6a6b72">Task</a>&amp;&amp; task);</div>
<div class="line"><a id="l00386" name="l00386"></a><span class="lineno">  386</span><span class="comment"></span> </div>
<div class="line"><a id="l00387" name="l00387"></a><span class="lineno">  387</span><span class="comment">/**</span></div>
<div class="line"><a id="l00388" name="l00388"></a><span class="lineno">  388</span><span class="comment"> * Assuming a planned thread pool will be receiving ~symmetrical load, and its UX-affecting (in particular, per-op</span></div>
<div class="line"><a id="l00389" name="l00389"></a><span class="lineno">  389</span><span class="comment"> * latency-affecting) operations are largely between processor and RAM: Returns the # of threads to store in that pool</span></div>
<div class="line"><a id="l00390" name="l00390"></a><span class="lineno">  390</span><span class="comment"> * for efficient performance.</span></div>
<div class="line"><a id="l00391" name="l00391"></a><span class="lineno">  391</span><span class="comment"> *</span></div>
<div class="line"><a id="l00392" name="l00392"></a><span class="lineno">  392</span><span class="comment"> * @see After the threads are created, use optimize_pinning_in_thread_pool() to complete</span></div>
<div class="line"><a id="l00393" name="l00393"></a><span class="lineno">  393</span><span class="comment"> * the work that targets this good performance.</span></div>
<div class="line"><a id="l00394" name="l00394"></a><span class="lineno">  394</span><span class="comment"> *</span></div>
<div class="line"><a id="l00395" name="l00395"></a><span class="lineno">  395</span><span class="comment"> * This will be used, by doc header contract, by all (as of this writing) Concurrent_task_loop subclasses if</span></div>
<div class="line"><a id="l00396" name="l00396"></a><span class="lineno">  396</span><span class="comment"> * so specified via `n_threads_or_zero == 0`.  So in that context one needn&#39;t call this directly.  However, it may be</span></div>
<div class="line"><a id="l00397" name="l00397"></a><span class="lineno">  397</span><span class="comment"> * useful directly when one is operating a thread pool but without a Concurrent_task_loop.</span></div>
<div class="line"><a id="l00398" name="l00398"></a><span class="lineno">  398</span><span class="comment"> *</span></div>
<div class="line"><a id="l00399" name="l00399"></a><span class="lineno">  399</span><span class="comment"> * @param logger_ptr</span></div>
<div class="line"><a id="l00400" name="l00400"></a><span class="lineno">  400</span><span class="comment"> *        Logger to use in this function.</span></div>
<div class="line"><a id="l00401" name="l00401"></a><span class="lineno">  401</span><span class="comment"> * @param est_hw_core_sharing_helps_algo</span></div>
<div class="line"><a id="l00402" name="l00402"></a><span class="lineno">  402</span><span class="comment"> *        Set this to `true` if you estimate the intended use for this thread pool is such that 2+ identically</span></div>
<div class="line"><a id="l00403" name="l00403"></a><span class="lineno">  403</span><span class="comment"> *        loaded pool threads sharing 1 physical core would handle the load (in total over those 2+ threads) better than</span></div>
<div class="line"><a id="l00404" name="l00404"></a><span class="lineno">  404</span><span class="comment"> *        just 1 thread using that same core would.  Set it to `false` otherwise.</span></div>
<div class="line"><a id="l00405" name="l00405"></a><span class="lineno">  405</span><span class="comment"> *        Note that, generally, this should be assumed `false`, unless there is significant cache locality between</span></div>
<div class="line"><a id="l00406" name="l00406"></a><span class="lineno">  406</span><span class="comment"> *        those 2+ threads, meaning they tend to work on the same cacheably-small area in memory at ~the same time.</span></div>
<div class="line"><a id="l00407" name="l00407"></a><span class="lineno">  407</span><span class="comment"> *        For example, parallel matrix multiplication algorithms can thus benefit and would set it to `true`; but</span></div>
<div class="line"><a id="l00408" name="l00408"></a><span class="lineno">  408</span><span class="comment"> *        that is the not the case by default; one would have to prove it, or design the algorithm with that in mind.</span></div>
<div class="line"><a id="l00409" name="l00409"></a><span class="lineno">  409</span><span class="comment"> * @return The number of threads mandated for the thread pool in question.</span></div>
<div class="line"><a id="l00410" name="l00410"></a><span class="lineno">  410</span><span class="comment"> */</span></div>
<div class="line"><a id="l00411" name="l00411"></a><span class="lineno">  411</span><span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code hl_function" href="namespaceflow_1_1async.html#adab04f47b40b92fffbe12bc33fadd223">optimal_worker_thread_count_per_pool</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr,</div>
<div class="line"><a id="l00412" name="l00412"></a><span class="lineno">  412</span>                                                  <span class="keywordtype">bool</span> est_hw_core_sharing_helps_algo);</div>
<div class="line"><a id="l00413" name="l00413"></a><span class="lineno">  413</span><span class="comment"></span> </div>
<div class="line"><a id="l00414" name="l00414"></a><span class="lineno">  414</span><span class="comment">/**</span></div>
<div class="line"><a id="l00415" name="l00415"></a><span class="lineno">  415</span><span class="comment"> * Assuming the same situation as documented for optimal_worker_thread_count_per_pool(), and that indeed</span></div>
<div class="line"><a id="l00416" name="l00416"></a><span class="lineno">  416</span><span class="comment"> * the pool now contains that number of running threads: Attempts to optimize thread-core-pinning behavior in that</span></div>
<div class="line"><a id="l00417" name="l00417"></a><span class="lineno">  417</span><span class="comment"> * pool for efficient performance.</span></div>
<div class="line"><a id="l00418" name="l00418"></a><span class="lineno">  418</span><span class="comment"> *</span></div>
<div class="line"><a id="l00419" name="l00419"></a><span class="lineno">  419</span><span class="comment"> * @see reset_thread_pinning(): related operation.</span></div>
<div class="line"><a id="l00420" name="l00420"></a><span class="lineno">  420</span><span class="comment"> *</span></div>
<div class="line"><a id="l00421" name="l00421"></a><span class="lineno">  421</span><span class="comment"> * ### Error condition ###</span></div>
<div class="line"><a id="l00422" name="l00422"></a><span class="lineno">  422</span><span class="comment"> * If an OS call fails, this will report error in standard Flow fashion.  That said, this would indicate some sort</span></div>
<div class="line"><a id="l00423" name="l00423"></a><span class="lineno">  423</span><span class="comment"> * of utter calamity of a situation; it might be reasonable to either both leave `err_code = null` and not-catch</span></div>
<div class="line"><a id="l00424" name="l00424"></a><span class="lineno">  424</span><span class="comment"> * the exception; or abort the process on any error.  In any case the situation will be logged.</span></div>
<div class="line"><a id="l00425" name="l00425"></a><span class="lineno">  425</span><span class="comment"> *</span></div>
<div class="line"><a id="l00426" name="l00426"></a><span class="lineno">  426</span><span class="comment"> * @see optimal_worker_thread_count_per_pool() first.  The two functions work together (one before, the other after</span></div>
<div class="line"><a id="l00427" name="l00427"></a><span class="lineno">  427</span><span class="comment"> *      spawning the threads).  Behavior is undefined if the two aren&#39;t used in coherent fashion, meaning one</span></div>
<div class="line"><a id="l00428" name="l00428"></a><span class="lineno">  428</span><span class="comment"> *      passed different values for same-named args.</span></div>
<div class="line"><a id="l00429" name="l00429"></a><span class="lineno">  429</span><span class="comment"> *</span></div>
<div class="line"><a id="l00430" name="l00430"></a><span class="lineno">  430</span><span class="comment"> * @note There is a to-do, as of this writing, to allow one to query system to auto-determine</span></div>
<div class="line"><a id="l00431" name="l00431"></a><span class="lineno">  431</span><span class="comment"> *       `hw_threads_is_grouping_collated` if desired.  See namespace flow::async doc header.</span></div>
<div class="line"><a id="l00432" name="l00432"></a><span class="lineno">  432</span><span class="comment"> *</span></div>
<div class="line"><a id="l00433" name="l00433"></a><span class="lineno">  433</span><span class="comment"> * @param logger_ptr</span></div>
<div class="line"><a id="l00434" name="l00434"></a><span class="lineno">  434</span><span class="comment"> *        Logger to use in this function.</span></div>
<div class="line"><a id="l00435" name="l00435"></a><span class="lineno">  435</span><span class="comment"> * @param threads_in_pool</span></div>
<div class="line"><a id="l00436" name="l00436"></a><span class="lineno">  436</span><span class="comment"> *        These raw threads, which must number `optimal_worker_thread_count_per_pool(same-relevant-args)`,</span></div>
<div class="line"><a id="l00437" name="l00437"></a><span class="lineno">  437</span><span class="comment"> *        comprise the pool in question.  They must be already spawned (e.g., have had some caller&#39;s code execute OK).</span></div>
<div class="line"><a id="l00438" name="l00438"></a><span class="lineno">  438</span><span class="comment"> * @param est_hw_core_sharing_helps_algo</span></div>
<div class="line"><a id="l00439" name="l00439"></a><span class="lineno">  439</span><span class="comment"> *        See optimal_worker_thread_count_per_pool().</span></div>
<div class="line"><a id="l00440" name="l00440"></a><span class="lineno">  440</span><span class="comment"> * @param est_hw_core_pinning_helps_algo</span></div>
<div class="line"><a id="l00441" name="l00441"></a><span class="lineno">  441</span><span class="comment"> *        Set this to `true` if you have reason to believe that pinning each of the pool&#39;s threads to N (N &gt;= 1)</span></div>
<div class="line"><a id="l00442" name="l00442"></a><span class="lineno">  442</span><span class="comment"> *        logical cores would improve performance in some way.  Set it to `false` otherwise.</span></div>
<div class="line"><a id="l00443" name="l00443"></a><span class="lineno">  443</span><span class="comment"> *        As of this writing I don&#39;t know why it would be `true` specifically; but it can be researched; and I know</span></div>
<div class="line"><a id="l00444" name="l00444"></a><span class="lineno">  444</span><span class="comment"> *        in practice some applications do (in fact) do it, so it&#39;s not necessarily worthless, at least.</span></div>
<div class="line"><a id="l00445" name="l00445"></a><span class="lineno">  445</span><span class="comment"> * @param hw_threads_is_grouping_collated</span></div>
<div class="line"><a id="l00446" name="l00446"></a><span class="lineno">  446</span><span class="comment"> *        When the number of physical cores does not equal # of logical cores (hardware threads) -- otherwise</span></div>
<div class="line"><a id="l00447" name="l00447"></a><span class="lineno">  447</span><span class="comment"> *        this arg is ignored -- this determines the pattern in which each set of</span></div>
<div class="line"><a id="l00448" name="l00448"></a><span class="lineno">  448</span><span class="comment"> *        2+ core-sharing hardware threads is arranged vs. the other sets.  When `false`, it&#39;s like ABCDABCD, meaning</span></div>
<div class="line"><a id="l00449" name="l00449"></a><span class="lineno">  449</span><span class="comment"> *        logical cores 0,4 share core, 1,5 share different core, 2,6 yet another, etc.  When `true`, it&#39;s like</span></div>
<div class="line"><a id="l00450" name="l00450"></a><span class="lineno">  450</span><span class="comment"> *        AABBCCDD instead.  It seems `true` is either rare or non-existent, but I do not know for sure.</span></div>
<div class="line"><a id="l00451" name="l00451"></a><span class="lineno">  451</span><span class="comment"> * @param err_code</span></div>
<div class="line"><a id="l00452" name="l00452"></a><span class="lineno">  452</span><span class="comment"> *        See `flow::Error_code` docs for error reporting semantics.  #Error_code generated:</span></div>
<div class="line"><a id="l00453" name="l00453"></a><span class="lineno">  453</span><span class="comment"> *        various native system errors.</span></div>
<div class="line"><a id="l00454" name="l00454"></a><span class="lineno">  454</span><span class="comment"> */</span></div>
<div class="line"><a id="l00455" name="l00455"></a><span class="lineno">  455</span><span class="keywordtype">void</span> <a class="code hl_function" href="namespaceflow_1_1async.html#a3e200db7e5375de21d2568004a85dcad">optimize_pinning_in_thread_pool</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr,</div>
<div class="line"><a id="l00456" name="l00456"></a><span class="lineno">  456</span>                                     <span class="keyword">const</span> std::vector&lt;util::Thread*&gt;&amp; threads_in_pool,</div>
<div class="line"><a id="l00457" name="l00457"></a><span class="lineno">  457</span>                                     <span class="keywordtype">bool</span> est_hw_core_sharing_helps_algo,</div>
<div class="line"><a id="l00458" name="l00458"></a><span class="lineno">  458</span>                                     <span class="keywordtype">bool</span> est_hw_core_pinning_helps_algo,</div>
<div class="line"><a id="l00459" name="l00459"></a><span class="lineno">  459</span>                                     <span class="keywordtype">bool</span> hw_threads_is_grouping_collated,</div>
<div class="line"><a id="l00460" name="l00460"></a><span class="lineno">  460</span>                                     <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>* err_code = <span class="keyword">nullptr</span>);</div>
<div class="line"><a id="l00461" name="l00461"></a><span class="lineno">  461</span><span class="comment"></span> </div>
<div class="line"><a id="l00462" name="l00462"></a><span class="lineno">  462</span><span class="comment">/**</span></div>
<div class="line"><a id="l00463" name="l00463"></a><span class="lineno">  463</span><span class="comment"> * Resets the processor-affinity of the given thread -- or calling thread -- to be managed as the OS deems best.</span></div>
<div class="line"><a id="l00464" name="l00464"></a><span class="lineno">  464</span><span class="comment"> *</span></div>
<div class="line"><a id="l00465" name="l00465"></a><span class="lineno">  465</span><span class="comment"> * The variant reset_this_thread_pinning(), equivalent to reset_thread_pinning() with args set to defaults,</span></div>
<div class="line"><a id="l00466" name="l00466"></a><span class="lineno">  466</span><span class="comment"> * is suitable to be passed to APIs that take a `void F()` function object</span></div>
<div class="line"><a id="l00467" name="l00467"></a><span class="lineno">  467</span><span class="comment"> * or function pointer; for example Single_thread_task_loop::start():</span></div>
<div class="line"><a id="l00468" name="l00468"></a><span class="lineno">  468</span><span class="comment"> *</span></div>
<div class="line"><a id="l00469" name="l00469"></a><span class="lineno">  469</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00470" name="l00470"></a><span class="lineno">  470</span><span class="comment"> *   flow::async::Single_thread_task_loop strong_confident_independent_thread{...};</span></div>
<div class="line"><a id="l00471" name="l00471"></a><span class="lineno">  471</span><span class="comment"> *   // It would inherit my core-affinity... so have it reset that early-on.</span></div>
<div class="line"><a id="l00472" name="l00472"></a><span class="lineno">  472</span><span class="comment"> *   strong_confident_independent_thread.start(flow::async::reset_this_thread_pinning);</span></div>
<div class="line"><a id="l00473" name="l00473"></a><span class="lineno">  473</span><span class="comment"> *   strong_confident_independent_thread.post([]()</span></div>
<div class="line"><a id="l00474" name="l00474"></a><span class="lineno">  474</span><span class="comment"> *   {</span></div>
<div class="line"><a id="l00475" name="l00475"></a><span class="lineno">  475</span><span class="comment"> *     // Do stuff!  Won&#39;t be tied down to any core(s)!</span></div>
<div class="line"><a id="l00476" name="l00476"></a><span class="lineno">  476</span><span class="comment"> *   });</span></div>
<div class="line"><a id="l00477" name="l00477"></a><span class="lineno">  477</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00478" name="l00478"></a><span class="lineno">  478</span><span class="comment"> *</span></div>
<div class="line"><a id="l00479" name="l00479"></a><span class="lineno">  479</span><span class="comment"> * ### Rationale ###</span></div>
<div class="line"><a id="l00480" name="l00480"></a><span class="lineno">  480</span><span class="comment"> * This might be useful in the face of the fact that at least some OS (Linux is one), when spawning thread T2 from</span></div>
<div class="line"><a id="l00481" name="l00481"></a><span class="lineno">  481</span><span class="comment"> * thread T1, by default have T2 inherit the processor-affinity of T1; so for example if T1 is pinned to core 7,</span></div>
<div class="line"><a id="l00482" name="l00482"></a><span class="lineno">  482</span><span class="comment"> * so will the new thread T2 be pinned to core 7 by default.  This may be desirable -- or not.</span></div>
<div class="line"><a id="l00483" name="l00483"></a><span class="lineno">  483</span><span class="comment"> *</span></div>
<div class="line"><a id="l00484" name="l00484"></a><span class="lineno">  484</span><span class="comment"> * In particular, a general library that starts background work threads, especially ones with which the lib&#39;s</span></div>
<div class="line"><a id="l00485" name="l00485"></a><span class="lineno">  485</span><span class="comment"> * user does not interact, might not want the default inheriting behavior but rather a thread behaving as independently</span></div>
<div class="line"><a id="l00486" name="l00486"></a><span class="lineno">  486</span><span class="comment"> * and efficiently as possible.</span></div>
<div class="line"><a id="l00487" name="l00487"></a><span class="lineno">  487</span><span class="comment"> *</span></div>
<div class="line"><a id="l00488" name="l00488"></a><span class="lineno">  488</span><span class="comment"> * Alternatively maybe you just want to undo optimize_pinning_in_thread_pool() or something.</span></div>
<div class="line"><a id="l00489" name="l00489"></a><span class="lineno">  489</span><span class="comment"> *</span></div>
<div class="line"><a id="l00490" name="l00490"></a><span class="lineno">  490</span><span class="comment"> * ### Error condition ###</span></div>
<div class="line"><a id="l00491" name="l00491"></a><span class="lineno">  491</span><span class="comment"> * See same section in optimize_pinning_in_thread_pool() doc header.</span></div>
<div class="line"><a id="l00492" name="l00492"></a><span class="lineno">  492</span><span class="comment"> *</span></div>
<div class="line"><a id="l00493" name="l00493"></a><span class="lineno">  493</span><span class="comment"> * @param logger_ptr</span></div>
<div class="line"><a id="l00494" name="l00494"></a><span class="lineno">  494</span><span class="comment"> *        Logger to use for logging inside.  An INFO message may be logged.  Null is as always allowed.</span></div>
<div class="line"><a id="l00495" name="l00495"></a><span class="lineno">  495</span><span class="comment"> * @param thread_else_ours</span></div>
<div class="line"><a id="l00496" name="l00496"></a><span class="lineno">  496</span><span class="comment"> *        The thread to affect; leave null to affect the calling thread.</span></div>
<div class="line"><a id="l00497" name="l00497"></a><span class="lineno">  497</span><span class="comment"> * @param err_code</span></div>
<div class="line"><a id="l00498" name="l00498"></a><span class="lineno">  498</span><span class="comment"> *        See `flow::Error_code` docs for error reporting semantics.  #Error_code generated:</span></div>
<div class="line"><a id="l00499" name="l00499"></a><span class="lineno">  499</span><span class="comment"> *        various native system errors.</span></div>
<div class="line"><a id="l00500" name="l00500"></a><span class="lineno">  500</span><span class="comment"> */</span></div>
<div class="line"><a id="l00501" name="l00501"></a><span class="lineno">  501</span><span class="keywordtype">void</span> <a class="code hl_function" href="namespaceflow_1_1async.html#a7fa5292ae2e7dddd11a7fe5228b1e574">reset_thread_pinning</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr = <span class="keyword">nullptr</span>,</div>
<div class="line"><a id="l00502" name="l00502"></a><span class="lineno">  502</span>                          <a class="code hl_typedef" href="namespaceflow_1_1util.html#af030c3119f060a9630afca31098a78a5">util::Thread</a>* thread_else_ours = <span class="keyword">nullptr</span>,</div>
<div class="line"><a id="l00503" name="l00503"></a><span class="lineno">  503</span>                          <a class="code hl_typedef" href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">Error_code</a>* err_code = <span class="keyword">nullptr</span>);</div>
<div class="line"><a id="l00504" name="l00504"></a><span class="lineno">  504</span><span class="comment"></span> </div>
<div class="line"><a id="l00505" name="l00505"></a><span class="lineno">  505</span><span class="comment">/**</span></div>
<div class="line"><a id="l00506" name="l00506"></a><span class="lineno">  506</span><span class="comment"> * Resets processor-affinity of the calling thread; does not log; and throws on extremely unlikely system error.</span></div>
<div class="line"><a id="l00507" name="l00507"></a><span class="lineno">  507</span><span class="comment"> * That is: simply calls `reset_thread_pinning()`.  @see reset_thread_pinning().</span></div>
<div class="line"><a id="l00508" name="l00508"></a><span class="lineno">  508</span><span class="comment"> *</span></div>
<div class="line"><a id="l00509" name="l00509"></a><span class="lineno">  509</span><span class="comment"> * This variant exists, so that one can pass it directly to APIs that expect a function object/pointer with</span></div>
<div class="line"><a id="l00510" name="l00510"></a><span class="lineno">  510</span><span class="comment"> * signature `void F()`; for example `std::function&lt;void ()&gt;` ctor or Single_thread_task_loop::start().</span></div>
<div class="line"><a id="l00511" name="l00511"></a><span class="lineno">  511</span><span class="comment"> *</span></div>
<div class="line"><a id="l00512" name="l00512"></a><span class="lineno">  512</span><span class="comment"> *</span></div>
<div class="line"><a id="l00513" name="l00513"></a><span class="lineno">  513</span><span class="comment"> * It is unfortunately not possible to, e.g., supply one of the form `void F(some_type some_arg = some_default)`:</span></div>
<div class="line"><a id="l00514" name="l00514"></a><span class="lineno">  514</span><span class="comment"> * the compiler doesn&#39;t like the presence of any args, even if they all have defaults.</span></div>
<div class="line"><a id="l00515" name="l00515"></a><span class="lineno">  515</span><span class="comment"> */</span></div>
<div class="line"><a id="l00516" name="l00516"></a><span class="lineno">  516</span><span class="keywordtype">void</span> <a class="code hl_function" href="namespaceflow_1_1async.html#a227e64eb71ec278f19d679d8411db627">reset_this_thread_pinning</a>();</div>
<div class="line"><a id="l00517" name="l00517"></a><span class="lineno">  517</span><span class="comment"></span> </div>
<div class="line"><a id="l00518" name="l00518"></a><span class="lineno">  518</span><span class="comment">/**</span></div>
<div class="line"><a id="l00519" name="l00519"></a><span class="lineno">  519</span><span class="comment"> * Given a boost.asio *completion handler* `handler` for a boost.asio `async_*()` action on some boost.asio I/O</span></div>
<div class="line"><a id="l00520" name="l00520"></a><span class="lineno">  520</span><span class="comment"> * object to be initiated in the immediate near future, returns a wrapped handler with the same signature</span></div>
<div class="line"><a id="l00521" name="l00521"></a><span class="lineno">  521</span><span class="comment"> * to be passed as the handler arg to that `async_*()` action, so that `handler()` will execute non-concurrently</span></div>
<div class="line"><a id="l00522" name="l00522"></a><span class="lineno">  522</span><span class="comment"> * with other tasks in `Op op`.  This is analogous to boost.asio&#39;s `bind_executor(Strand, Handler)` (which</span></div>
<div class="line"><a id="l00523" name="l00523"></a><span class="lineno">  523</span><span class="comment"> * replaces boost.asio&#39;s now-deprecated `util::Strand::wrap(Handler)`).</span></div>
<div class="line"><a id="l00524" name="l00524"></a><span class="lineno">  524</span><span class="comment"> *</span></div>
<div class="line"><a id="l00525" name="l00525"></a><span class="lineno">  525</span><span class="comment"> * The mechanics of using this are explained in Concurrent_task_loop doc header.  Using this in any other</span></div>
<div class="line"><a id="l00526" name="l00526"></a><span class="lineno">  526</span><span class="comment"> * fashion leads to undefined behavior.</span></div>
<div class="line"><a id="l00527" name="l00527"></a><span class="lineno">  527</span><span class="comment"> *</span></div>
<div class="line"><a id="l00528" name="l00528"></a><span class="lineno">  528</span><span class="comment"> * @tparam Handler</span></div>
<div class="line"><a id="l00529" name="l00529"></a><span class="lineno">  529</span><span class="comment"> *         boost.asio handlers are, essentially, all `void`-returning but can take various arg sets.</span></div>
<div class="line"><a id="l00530" name="l00530"></a><span class="lineno">  530</span><span class="comment"> *         E.g., util::Timer (a/k/a `boost::asio::basic_waitable_timer`) expects a handler that takes only an</span></div>
<div class="line"><a id="l00531" name="l00531"></a><span class="lineno">  531</span><span class="comment"> *         `Error_code`; while `boost::asio::ip:tcp::socket::read_some()` expects one to take bytes-received `size_t`</span></div>
<div class="line"><a id="l00532" name="l00532"></a><span class="lineno">  532</span><span class="comment"> *         and an `Error_code`.  This template supports all handlers via `auto` magic.</span></div>
<div class="line"><a id="l00533" name="l00533"></a><span class="lineno">  533</span><span class="comment"> * @param loop</span></div>
<div class="line"><a id="l00534" name="l00534"></a><span class="lineno">  534</span><span class="comment"> *        Active loop that spawned `Op op`.</span></div>
<div class="line"><a id="l00535" name="l00535"></a><span class="lineno">  535</span><span class="comment"> * @param op</span></div>
<div class="line"><a id="l00536" name="l00536"></a><span class="lineno">  536</span><span class="comment"> *        See 3-arg Concurrent_task_loop::post().</span></div>
<div class="line"><a id="l00537" name="l00537"></a><span class="lineno">  537</span><span class="comment"> * @param handler</span></div>
<div class="line"><a id="l00538" name="l00538"></a><span class="lineno">  538</span><span class="comment"> *        Completion handler for the boost.asio `async_*()` operation to be initiated soon.</span></div>
<div class="line"><a id="l00539" name="l00539"></a><span class="lineno">  539</span><span class="comment"> *        It may be `move`d and saved.</span></div>
<div class="line"><a id="l00540" name="l00540"></a><span class="lineno">  540</span><span class="comment"> * @return A completion handler that will act as `handler()` but also satisfying the constraints of</span></div>
<div class="line"><a id="l00541" name="l00541"></a><span class="lineno">  541</span><span class="comment"> *         `Op op`.</span></div>
<div class="line"><a id="l00542" name="l00542"></a><span class="lineno">  542</span><span class="comment"> */</span></div>
<div class="line"><a id="l00543" name="l00543"></a><span class="lineno">  543</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Handler&gt;</div>
<div class="line"><a id="l00544" name="l00544"></a><span class="lineno">  544</span><span class="keyword">auto</span> <a class="code hl_function" href="namespaceflow_1_1async.html#af90c1e763d49c3f3033a74871e897394">asio_handler_via_op</a>(Concurrent_task_loop* loop, <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">Op</a>&amp; op, Handler&amp;&amp; handler);</div>
<div class="line"><a id="l00545" name="l00545"></a><span class="lineno">  545</span><span class="comment"></span> </div>
<div class="line"><a id="l00546" name="l00546"></a><span class="lineno">  546</span><span class="comment">/**</span></div>
<div class="line"><a id="l00547" name="l00547"></a><span class="lineno">  547</span><span class="comment"> * Template specialization model for operation that obtains the underlying execution context, such as a</span></div>
<div class="line"><a id="l00548" name="l00548"></a><span class="lineno">  548</span><span class="comment"> * util::Task_engine or util::Strand, stored in an async::Op generated by the given Concurrent_task_loop.</span></div>
<div class="line"><a id="l00549" name="l00549"></a><span class="lineno">  549</span><span class="comment"> * Each subclass (impl) of Concurrent_task_loop shall provide a specialization of this template with</span></div>
<div class="line"><a id="l00550" name="l00550"></a><span class="lineno">  550</span><span class="comment"> * `Exec_ctx_ptr` template param being the appropriate boost.asio-compatible execution context type for that</span></div>
<div class="line"><a id="l00551" name="l00551"></a><span class="lineno">  551</span><span class="comment"> * loop type&#39;s `Op create_op()`.</span></div>
<div class="line"><a id="l00552" name="l00552"></a><span class="lineno">  552</span><span class="comment"> *</span></div>
<div class="line"><a id="l00553" name="l00553"></a><span class="lineno">  553</span><span class="comment"> * The mechanics of using this are explained in Concurrent_task_loop doc header.  Beyond that please see the particular</span></div>
<div class="line"><a id="l00554" name="l00554"></a><span class="lineno">  554</span><span class="comment"> * specialization&#39;s doc header.</span></div>
<div class="line"><a id="l00555" name="l00555"></a><span class="lineno">  555</span><span class="comment"> *</span></div>
<div class="line"><a id="l00556" name="l00556"></a><span class="lineno">  556</span><span class="comment"> * @relatesalso Concurrent_task_loop</span></div>
<div class="line"><a id="l00557" name="l00557"></a><span class="lineno">  557</span><span class="comment"> * @tparam Exec_ctx_ptr</span></div>
<div class="line"><a id="l00558" name="l00558"></a><span class="lineno">  558</span><span class="comment"> *         A pointer type (raw or smart) pointing to an execution context type satisfying</span></div>
<div class="line"><a id="l00559" name="l00559"></a><span class="lineno">  559</span><span class="comment"> *         boost.asio&#39;s &quot;execution context&quot; concept.  As of this writing the known values would be</span></div>
<div class="line"><a id="l00560" name="l00560"></a><span class="lineno">  560</span><span class="comment"> *         pointers to util::Task_engine and util::Strand, but really it depends on the particular</span></div>
<div class="line"><a id="l00561" name="l00561"></a><span class="lineno">  561</span><span class="comment"> *         subclass of Concurrent_task_loop for the `*loop` arg.  See its doc header near</span></div>
<div class="line"><a id="l00562" name="l00562"></a><span class="lineno">  562</span><span class="comment"> *         the particular Concurrent_task_loop subclass.</span></div>
<div class="line"><a id="l00563" name="l00563"></a><span class="lineno">  563</span><span class="comment"> * @param loop</span></div>
<div class="line"><a id="l00564" name="l00564"></a><span class="lineno">  564</span><span class="comment"> *        Loop object that, one way or another, generated and returned `op`.</span></div>
<div class="line"><a id="l00565" name="l00565"></a><span class="lineno">  565</span><span class="comment"> * @param op</span></div>
<div class="line"><a id="l00566" name="l00566"></a><span class="lineno">  566</span><span class="comment"> *        async::Op from `*loop` from which to extract the execution context object on which you&#39;d like to perform</span></div>
<div class="line"><a id="l00567" name="l00567"></a><span class="lineno">  567</span><span class="comment"> *        custom boost.asio work.</span></div>
<div class="line"><a id="l00568" name="l00568"></a><span class="lineno">  568</span><span class="comment"> * @return Pointer to a mutable execution context object.</span></div>
<div class="line"><a id="l00569" name="l00569"></a><span class="lineno">  569</span><span class="comment"> */</span></div>
<div class="line"><a id="l00570" name="l00570"></a><span class="lineno">  570</span><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Exec_ctx_ptr&gt;</div>
<div class="line"><a id="l00571" name="l00571"></a><span class="lineno"><a class="line" href="classflow_1_1async_1_1Concurrent__task__loop.html#a7f2f976a53191a3b0cd28898bb23c551">  571</a></span>Exec_ctx_ptr <a class="code hl_function" href="classflow_1_1async_1_1Concurrent__task__loop.html#a7f2f976a53191a3b0cd28898bb23c551">op_to_exec_ctx</a>(<a class="code hl_class" href="classflow_1_1async_1_1Concurrent__task__loop.html">Concurrent_task_loop</a>* loop, <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">Op</a>&amp; op);</div>
<div class="line"><a id="l00572" name="l00572"></a><span class="lineno">  572</span><span class="comment"></span> </div>
<div class="line"><a id="l00573" name="l00573"></a><span class="lineno">  573</span><span class="comment">/**</span></div>
<div class="line"><a id="l00574" name="l00574"></a><span class="lineno">  574</span><span class="comment"> * Template specialization for operation that obtains the underlying execution context, in this case</span></div>
<div class="line"><a id="l00575" name="l00575"></a><span class="lineno">  575</span><span class="comment"> * a util::Task_engine, stored in an async::Op generated by the given Segregated_thread_task_loop.</span></div>
<div class="line"><a id="l00576" name="l00576"></a><span class="lineno">  576</span><span class="comment"> * While `*loop` is running, the Task_engine is running in exactly 1 thread.</span></div>
<div class="line"><a id="l00577" name="l00577"></a><span class="lineno">  577</span><span class="comment"> *</span></div>
<div class="line"><a id="l00578" name="l00578"></a><span class="lineno">  578</span><span class="comment"> * Note Concurrent_task_loop::task_engine() is spiritually related to this function; but while that one gives one</span></div>
<div class="line"><a id="l00579" name="l00579"></a><span class="lineno">  579</span><span class="comment"> * a random thread&#39;s util::Task_engine, this one returns the specific thread&#39;s assigned to a multi-step async op `op`.</span></div>
<div class="line"><a id="l00580" name="l00580"></a><span class="lineno">  580</span><span class="comment"> *</span></div>
<div class="line"><a id="l00581" name="l00581"></a><span class="lineno">  581</span><span class="comment"> * @see Concurrent_task_loop doc header for discussion.</span></div>
<div class="line"><a id="l00582" name="l00582"></a><span class="lineno">  582</span><span class="comment"> * @relatesalso Segregated_thread_task_loop</span></div>
<div class="line"><a id="l00583" name="l00583"></a><span class="lineno">  583</span><span class="comment"> *</span></div>
<div class="line"><a id="l00584" name="l00584"></a><span class="lineno">  584</span><span class="comment"> * @param loop</span></div>
<div class="line"><a id="l00585" name="l00585"></a><span class="lineno">  585</span><span class="comment"> *        Loop object that, one way or another, generated and returned `op`.</span></div>
<div class="line"><a id="l00586" name="l00586"></a><span class="lineno">  586</span><span class="comment"> *        Behavior is undefined if the concrete pointed-to type is not Segregated_thread_task_loop.</span></div>
<div class="line"><a id="l00587" name="l00587"></a><span class="lineno">  587</span><span class="comment"> *        (assertion may trip).</span></div>
<div class="line"><a id="l00588" name="l00588"></a><span class="lineno">  588</span><span class="comment"> * @param op</span></div>
<div class="line"><a id="l00589" name="l00589"></a><span class="lineno">  589</span><span class="comment"> *        async::Op from `*loop` from which to extract the execution context on which you&#39;d like to perform</span></div>
<div class="line"><a id="l00590" name="l00590"></a><span class="lineno">  590</span><span class="comment"> *        custom boost.asio work.  Behavior is undefined if it is not from `*loop` (assertion may trip).</span></div>
<div class="line"><a id="l00591" name="l00591"></a><span class="lineno">  591</span><span class="comment"> * @return Pointer to a mutable util::Task_engine `E` used by `*loop`.</span></div>
<div class="line"><a id="l00592" name="l00592"></a><span class="lineno">  592</span><span class="comment"> */</span></div>
<div class="line"><a id="l00593" name="l00593"></a><span class="lineno">  593</span><span class="keyword">template</span>&lt;&gt;</div>
<div class="line"><a id="l00594" name="l00594"></a><span class="lineno">  594</span><a class="code hl_typedef" href="namespaceflow_1_1async.html#a968806f54b14c697fd76b3339a2bdbbf">Task_engine_ptr</a> <a class="code hl_function" href="namespaceflow_1_1async.html#ad70c594985b402d9024b80370611fc1c">op_to_exec_ctx&lt;Task_engine_ptr&gt;</a>(<a class="code hl_class" href="classflow_1_1async_1_1Concurrent__task__loop.html">Concurrent_task_loop</a>* loop, <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">Op</a>&amp; op);</div>
<div class="line"><a id="l00595" name="l00595"></a><span class="lineno">  595</span><span class="comment"></span> </div>
<div class="line"><a id="l00596" name="l00596"></a><span class="lineno">  596</span><span class="comment">/**</span></div>
<div class="line"><a id="l00597" name="l00597"></a><span class="lineno">  597</span><span class="comment"> * Template specialization for operation that obtains the underlying execution context, in this case</span></div>
<div class="line"><a id="l00598" name="l00598"></a><span class="lineno">  598</span><span class="comment"> * a util::Strand, stored in an async::Op generated by the given Cross_thread_task_loop.</span></div>
<div class="line"><a id="l00599" name="l00599"></a><span class="lineno">  599</span><span class="comment"> *</span></div>
<div class="line"><a id="l00600" name="l00600"></a><span class="lineno">  600</span><span class="comment"> * boost.asio tip: The returned util::Strand may be useful not only as an argument to `bind_executor()`</span></div>
<div class="line"><a id="l00601" name="l00601"></a><span class="lineno">  601</span><span class="comment"> * (formerly `Strand::wrap()`, now deprecated) but can also be passed in lieu of a util::Task_engine into</span></div>
<div class="line"><a id="l00602" name="l00602"></a><span class="lineno">  602</span><span class="comment"> * boost.asio-enabled I/O object constructors (util::Timer, `boost::asio::ip::tcp::socket`, etc.).  The latter use</span></div>
<div class="line"><a id="l00603" name="l00603"></a><span class="lineno">  603</span><span class="comment"> * uses the `Strand` as an &quot;execution context.&quot;</span></div>
<div class="line"><a id="l00604" name="l00604"></a><span class="lineno">  604</span><span class="comment"> *</span></div>
<div class="line"><a id="l00605" name="l00605"></a><span class="lineno">  605</span><span class="comment"> * Note Concurrent_task_loop::task_engine() is spiritually related to this function; but while that one gives one</span></div>
<div class="line"><a id="l00606" name="l00606"></a><span class="lineno">  606</span><span class="comment"> * a util::Task_engine, which corresponds to the entire thread pool, this one returns an execution context specifically</span></div>
<div class="line"><a id="l00607" name="l00607"></a><span class="lineno">  607</span><span class="comment"> * assigned to a multi-step async op `op`.</span></div>
<div class="line"><a id="l00608" name="l00608"></a><span class="lineno">  608</span><span class="comment"> *</span></div>
<div class="line"><a id="l00609" name="l00609"></a><span class="lineno">  609</span><span class="comment"> * @see Concurrent_task_loop doc header for discussion.</span></div>
<div class="line"><a id="l00610" name="l00610"></a><span class="lineno">  610</span><span class="comment"> * @relatesalso Cross_thread_task_loop</span></div>
<div class="line"><a id="l00611" name="l00611"></a><span class="lineno">  611</span><span class="comment"> *</span></div>
<div class="line"><a id="l00612" name="l00612"></a><span class="lineno">  612</span><span class="comment"> * @param loop</span></div>
<div class="line"><a id="l00613" name="l00613"></a><span class="lineno">  613</span><span class="comment"> *        Loop object that, one way or another, generated and returned `op`.</span></div>
<div class="line"><a id="l00614" name="l00614"></a><span class="lineno">  614</span><span class="comment"> *        Behavior is undefined if the concrete pointed-to type is not Cross_thread_task_loop.</span></div>
<div class="line"><a id="l00615" name="l00615"></a><span class="lineno">  615</span><span class="comment"> *        (assertion may trip).</span></div>
<div class="line"><a id="l00616" name="l00616"></a><span class="lineno">  616</span><span class="comment"> * @param op</span></div>
<div class="line"><a id="l00617" name="l00617"></a><span class="lineno">  617</span><span class="comment"> *        async::Op from `*loop` from which to extract the execution context on which you&#39;d like to perform</span></div>
<div class="line"><a id="l00618" name="l00618"></a><span class="lineno">  618</span><span class="comment"> *        custom boost.asio work.  Behavior is undefined if it is not from `*loop` (assertion may trip).</span></div>
<div class="line"><a id="l00619" name="l00619"></a><span class="lineno">  619</span><span class="comment"> * @return Pointer to a mutable util::Strand created from util::Task_engine `E` such that</span></div>
<div class="line"><a id="l00620" name="l00620"></a><span class="lineno">  620</span><span class="comment"> *         `loop-&gt;task_engine() == &amp;E`.</span></div>
<div class="line"><a id="l00621" name="l00621"></a><span class="lineno">  621</span><span class="comment"> */</span></div>
<div class="line"><a id="l00622" name="l00622"></a><span class="lineno">  622</span><span class="keyword">template</span>&lt;&gt;</div>
<div class="line"><a id="l00623" name="l00623"></a><span class="lineno">  623</span><a class="code hl_typedef" href="namespaceflow_1_1async.html#a2b92feccafa90bce16db57131c0fcd9e">Strand_ptr</a> <a class="code hl_function" href="namespaceflow_1_1async.html#a5dad6aeb3cf4219833e18343bec0b423">op_to_exec_ctx&lt;Strand_ptr&gt;</a>(<a class="code hl_class" href="classflow_1_1async_1_1Concurrent__task__loop.html">Concurrent_task_loop</a>* loop, <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">Op</a>&amp; op);</div>
<div class="line"><a id="l00624" name="l00624"></a><span class="lineno">  624</span> </div>
<div class="line"><a id="l00625" name="l00625"></a><span class="lineno">  625</span>} <span class="comment">// namespace flow::async</span></div>
<div class="ttc" id="aclassflow_1_1Function_html"><div class="ttname"><a href="classflow_1_1Function.html">flow::Function</a></div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00512">common.hpp:512</a></div></div>
<div class="ttc" id="aclassflow_1_1async_1_1Concurrent__task__loop_html"><div class="ttname"><a href="classflow_1_1async_1_1Concurrent__task__loop.html">flow::async::Concurrent_task_loop</a></div><div class="ttdoc">The core flow::async interface, providing an optionally multi-threaded thread pool onto which runnabl...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8hpp_source.html#l00322">concurrent_task_loop.hpp:324</a></div></div>
<div class="ttc" id="aclassflow_1_1async_1_1Concurrent__task__loop_html_a7f2f976a53191a3b0cd28898bb23c551"><div class="ttname"><a href="classflow_1_1async_1_1Concurrent__task__loop.html#a7f2f976a53191a3b0cd28898bb23c551">flow::async::Concurrent_task_loop::op_to_exec_ctx</a></div><div class="ttdeci">Exec_ctx_ptr op_to_exec_ctx(Concurrent_task_loop *loop, const Op &amp;op)</div><div class="ttdoc">Template specialization model for operation that obtains the underlying execution context,...</div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="adetail_2async__fwd_8hpp_html"><div class="ttname"><a href="detail_2async__fwd_8hpp.html">async_fwd.hpp</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html"><div class="ttname"><a href="namespaceflow_1_1async.html">flow::async</a></div><div class="ttdoc">Flow module containing tools enabling multi-threaded event loops operating under the asynchronous-tas...</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00074">async_fwd.hpp:75</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a024042c64b7dc544a7a5587afa4b1949"><div class="ttname"><a href="namespaceflow_1_1async.html#a024042c64b7dc544a7a5587afa4b1949">flow::async::Op</a></div><div class="ttdeci">boost::any Op</div><div class="ttdoc">An object of this opaque type represents a collection of 1 or more async::Task, past or future,...</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00153">async_fwd.hpp:153</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485">flow::async::Synchronicity</a></div><div class="ttdeci">Synchronicity</div><div class="ttdoc">Enumeration indicating the manner in which asio_exec_ctx_post(), and various boost....</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00222">async_fwd.hpp:223</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485a4d7a5700444c0570af37b1f9bcc6eb1f"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485a4d7a5700444c0570af37b1f9bcc6eb1f">flow::async::Synchronicity::S_ASYNC</a></div><div class="ttdeci">@ S_ASYNC</div><div class="ttdoc">Simply post the given task to execute asynchronously in some execution context – as soon as the conte...</div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485a57525f29ac96f4edd56c951e7d7c7b25"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485a57525f29ac96f4edd56c951e7d7c7b25">flow::async::Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION</a></div><div class="ttdeci">@ S_ASYNC_AND_AWAIT_CONCURRENT_COMPLETION</div><div class="ttdoc">Same as Synchronicity::S_ASYNC but the posting routine then waits as long as necessary for the given ...</div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485ae9a9ae292ea3fbbe3b313348dcec0846"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485ae9a9ae292ea3fbbe3b313348dcec0846">flow::async::Synchronicity::S_ASYNC_AND_AWAIT_CONCURRENT_START</a></div><div class="ttdeci">@ S_ASYNC_AND_AWAIT_CONCURRENT_START</div><div class="ttdoc">Same as Synchronicity::S_ASYNC but the posting routine then waits as long as necessary for the given ...</div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a0a06794b16b72f2829ce3353557c8485aff6bc53ee6c14f2eee463c06d9dff01f"><div class="ttname"><a href="namespaceflow_1_1async.html#a0a06794b16b72f2829ce3353557c8485aff6bc53ee6c14f2eee463c06d9dff01f">flow::async::Synchronicity::S_OPPORTUNISTIC_SYNC_ELSE_ASYNC</a></div><div class="ttdeci">@ S_OPPORTUNISTIC_SYNC_ELSE_ASYNC</div><div class="ttdoc">Execute the given task synchronously, if the scheduler determines that the calling thread is in its t...</div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a227e64eb71ec278f19d679d8411db627"><div class="ttname"><a href="namespaceflow_1_1async.html#a227e64eb71ec278f19d679d8411db627">flow::async::reset_this_thread_pinning</a></div><div class="ttdeci">void reset_this_thread_pinning()</div><div class="ttdoc">Resets processor-affinity of the calling thread; does not log; and throws on extremely unlikely syste...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8cpp_source.html#l00309">concurrent_task_loop.cpp:309</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a24567271e97a67d3cae6bd8bf8dc63c4"><div class="ttname"><a href="namespaceflow_1_1async.html#a24567271e97a67d3cae6bd8bf8dc63c4">flow::async::asio_exec_ctx_post</a></div><div class="ttdeci">void asio_exec_ctx_post(log::Logger *logger_ptr, Execution_context *exec_ctx, Synchronicity synchronicity, Task &amp;&amp;task)</div><div class="ttdoc">An extension of boost.asio's post() and dispatch() free function templates, this free function templa...</div><div class="ttdef"><b>Definition:</b> <a href="async_2util_8hpp_source.html#l00031">util.hpp:31</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a2b92feccafa90bce16db57131c0fcd9e"><div class="ttname"><a href="namespaceflow_1_1async.html#a2b92feccafa90bce16db57131c0fcd9e">flow::async::Strand_ptr</a></div><div class="ttdeci">boost::shared_ptr&lt; util::Strand &gt; Strand_ptr</div><div class="ttdoc">Short-hand for ref-counted pointer to util::Strand.</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00212">async_fwd.hpp:212</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a3e200db7e5375de21d2568004a85dcad"><div class="ttname"><a href="namespaceflow_1_1async.html#a3e200db7e5375de21d2568004a85dcad">flow::async::optimize_pinning_in_thread_pool</a></div><div class="ttdeci">void optimize_pinning_in_thread_pool(log::Logger *logger_ptr, const std::vector&lt; util::Thread * &gt; &amp;threads_in_pool, bool est_hw_core_sharing_helps_algo, bool est_hw_core_pinning_helps_algo, bool hw_threads_is_grouping_collated, Error_code *err_code=nullptr)</div><div class="ttdoc">Assuming the same situation as documented for optimal_worker_thread_count_per_pool(),...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8cpp_source.html#l00080">concurrent_task_loop.cpp:80</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a5dad6aeb3cf4219833e18343bec0b423"><div class="ttname"><a href="namespaceflow_1_1async.html#a5dad6aeb3cf4219833e18343bec0b423">flow::async::op_to_exec_ctx&lt; Strand_ptr &gt;</a></div><div class="ttdeci">Strand_ptr op_to_exec_ctx&lt; Strand_ptr &gt;(Concurrent_task_loop *loop, const Op &amp;op)</div><div class="ttdoc">Template specialization for operation that obtains the underlying execution context,...</div><div class="ttdef"><b>Definition:</b> <a href="x__thread__task__loop_8cpp_source.html#l00420">x_thread_task_loop.cpp:420</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a7fa5292ae2e7dddd11a7fe5228b1e574"><div class="ttname"><a href="namespaceflow_1_1async.html#a7fa5292ae2e7dddd11a7fe5228b1e574">flow::async::reset_thread_pinning</a></div><div class="ttdeci">void reset_thread_pinning(log::Logger *logger_ptr=nullptr, util::Thread *thread_else_ours=nullptr, Error_code *err_code=nullptr)</div><div class="ttdoc">Resets the processor-affinity of the given thread – or calling thread – to be managed as the OS deems...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8cpp_source.html#l00261">concurrent_task_loop.cpp:261</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_a968806f54b14c697fd76b3339a2bdbbf"><div class="ttname"><a href="namespaceflow_1_1async.html#a968806f54b14c697fd76b3339a2bdbbf">flow::async::Task_engine_ptr</a></div><div class="ttdeci">boost::shared_ptr&lt; util::Task_engine &gt; Task_engine_ptr</div><div class="ttdoc">Short-hand for reference-counting pointer to a mutable util::Task_engine (a/k/a boost::asio::io_conte...</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00198">async_fwd.hpp:198</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_ad70c594985b402d9024b80370611fc1c"><div class="ttname"><a href="namespaceflow_1_1async.html#ad70c594985b402d9024b80370611fc1c">flow::async::op_to_exec_ctx&lt; Task_engine_ptr &gt;</a></div><div class="ttdeci">Task_engine_ptr op_to_exec_ctx&lt; Task_engine_ptr &gt;(Concurrent_task_loop *loop, const Op &amp;op)</div><div class="ttdoc">Template specialization for operation that obtains the underlying execution context,...</div><div class="ttdef"><b>Definition:</b> <a href="segregated__thread__task__loop_8cpp_source.html#l00419">segregated_thread_task_loop.cpp:419</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_adab04f47b40b92fffbe12bc33fadd223"><div class="ttname"><a href="namespaceflow_1_1async.html#adab04f47b40b92fffbe12bc33fadd223">flow::async::optimal_worker_thread_count_per_pool</a></div><div class="ttdeci">unsigned int optimal_worker_thread_count_per_pool(log::Logger *logger_ptr, bool est_hw_core_sharing_helps_algo)</div><div class="ttdoc">Assuming a planned thread pool will be receiving ~symmetrical load, and its UX-affecting (in particul...</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8cpp_source.html#l00037">concurrent_task_loop.cpp:37</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_af35fb65bdea1a3a92929ec2c4a6a6b72"><div class="ttname"><a href="namespaceflow_1_1async.html#af35fb65bdea1a3a92929ec2c4a6a6b72">flow::async::Task</a></div><div class="ttdeci">Function&lt; void()&gt; Task</div><div class="ttdoc">Short-hand for a task that can be posted for execution by a Concurrent_task_loop or flow::util::Task_...</div><div class="ttdef"><b>Definition:</b> <a href="async__fwd_8hpp_source.html#l00096">async_fwd.hpp:96</a></div></div>
<div class="ttc" id="anamespaceflow_1_1async_html_af90c1e763d49c3f3033a74871e897394"><div class="ttname"><a href="namespaceflow_1_1async.html#af90c1e763d49c3f3033a74871e897394">flow::async::asio_handler_via_op</a></div><div class="ttdeci">auto asio_handler_via_op(Concurrent_task_loop *loop, const Op &amp;op, Handler &amp;&amp;handler)</div><div class="ttdoc">Given a boost.asio completion handler handler for a boost.asio async_*() action on some boost....</div><div class="ttdef"><b>Definition:</b> <a href="concurrent__task__loop_8hpp_source.html#l00691">concurrent_task_loop.hpp:691</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_aafa03984c5012ef7db2e7d01b6909a83"><div class="ttname"><a href="namespaceflow_1_1util.html#aafa03984c5012ef7db2e7d01b6909a83">flow::util::Scheduled_task</a></div><div class="ttdeci">Function&lt; void(bool short_fire)&gt; Scheduled_task</div><div class="ttdoc">Short-hand for tasks that can be scheduled/fired by schedule_task_from_now() and similar.</div><div class="ttdef"><b>Definition:</b> <a href="sched__task__fwd_8hpp_source.html#l00059">sched_task_fwd.hpp:59</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_af030c3119f060a9630afca31098a78a5"><div class="ttname"><a href="namespaceflow_1_1util.html#af030c3119f060a9630afca31098a78a5">flow::util::Thread</a></div><div class="ttdeci">boost::thread Thread</div><div class="ttdoc">Short-hand for standard thread class.</div><div class="ttdef"><b>Definition:</b> <a href="util__fwd_8hpp_source.html#l00078">util_fwd.hpp:78</a></div></div>
<div class="ttc" id="anamespaceflow_html_a29eaaa9d0fac4ce87d8b969222dbed09"><div class="ttname"><a href="namespaceflow.html#a29eaaa9d0fac4ce87d8b969222dbed09">flow::Error_code</a></div><div class="ttdeci">boost::system::error_code Error_code</div><div class="ttdoc">Short-hand for a boost.system error code (which basically encapsulates an integer/enum error code and...</div><div class="ttdef"><b>Definition:</b> <a href="common_8hpp_source.html#l00508">common.hpp:508</a></div></div>
<div class="ttc" id="asched__task__fwd_8hpp_html"><div class="ttname"><a href="sched__task__fwd_8hpp.html">sched_task_fwd.hpp</a></div></div>
<div class="ttc" id="autil__fwd_8hpp_html"><div class="ttname"><a href="util__fwd_8hpp.html">util_fwd.hpp</a></div></div>
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